#!/usr/bin/env bash
### 0到9之间每个数的平方
x=0
### x小于10
while [[ ${x} -lt 10 ]]; do
echo $((x * x))
x=$((x + 1))
done
# Output:
# 0
# 1
# 4
# 9
# 16
# 25
# 36
# 49
# 64
# 81